5. Protection and control functions
5.1 Motor protection devices
The motors have three thermal protectors and two
moisture switches connected in series. Protectors
and switches are connected in two separate circuits.
The thermal protectors are reversible, and the
moisture switches are irreversible. The thermal
protection circuit, conductors 1 and 3, and the
moisture protection circuit, conductors 2 and 3, have
separate outputs to enable separate alarms if the
motor is overheated or affected by moisture.
All other sensor connections are either led out of the
motor, sensor version D, through conductors 4 to 9,
or connected to the sensor board, sensor version B,
and led out of the motor through conductors 4 and 5.
5.2 Pump controller
The liquid level can be controlled by Grundfos LC 231
and LC 241 level controllers. The pumps are
protected by thermal switches connected to the LC
controller or a CU 100 control unit.
5.2.1 LC level controllers
Suitable level controllers:
•
LC 231: compact solution with certified motor
protection for single- and dual-pump versions.
•
LC 241: cabinet solution offering modularity and
customisation for single- and dual-pump versions.
In the following description, "level switches" can be air
bells, float switches or electrodes depending on the
selected pump controller.
Depending on the security levels and the number of
pumps, level switches can be used in the following
settings:
•
Dry run (optional)
•
Stop
•
Start pump 1 (single-pump version)
•
Start pump 2 (dual-pump version)
•
High level (optional).
Analog level transmitters can be used, and all levels
can be customised. Level switches can be used with
level transmitters, for dry-run protection and high-
level alarm.
When installing the level switches, observe the
following:
•
To prevent air intake and vibrations, install the
stop level switch, so the pump is stopped before
the liquid level is lowered to the middle of the
motor housing.
•
Install the start level switch, so the pump is started
at the required level. The pump must always be
started before the liquid level reaches the bottom
inlet pipe.
•
Always install the high-level alarm switch about 10
cm above the start level switch. However, the
alarm must always be given before the liquid level
reaches the inlet pipe.
For further settings, see the installation and operating
instructions for the selected level controller.
The pump must not run dry.
Install an additional level switch to ensure
the pump is stopped in case the stop level
switch is not operating.
The pump must be stopped when the liq-
uid level reaches the upper edge of the
clamp.
Float switches used in potentially explo-
sive environments must be approved for
this application. They must be connected
to the Grundfos LC 231 or LC 241 level
controller by an intrinsically safe barrier to
ensure safe circuit. In potentially explosive
environments, the anti-seizing function
must be disabled on pump controllers.
Do not install the pump controller in a po-
tentially explosive atmosphere.
Level switches must comply with IEC/EC
50495, Annex D.
5.3 IO 113
IO 113 forms the interface between a Grundfos
sewage and wastewater pump with analog and digital
sensors and the pump controller. The most important
sensor data are indicated on the front panel.
One pump can be connected to an IO 113 module.
Together with the sensors, IO 113 forms a galvanic
separation between the motor voltage in the pump
and the controller.
IO 113 is capable of the following as standard:
•
protect the pump against overheating
•
monitor the status of:
- motor winding temperature
- leakage through WIO sensor
- moisture in the pump.
•
measure the stator insulation resistance.
•
stop the pump in case of alarm
•
remotely monitor the pump through RS-485
communication, Modbus or GENIbus
•
control the pump by a frequency converter.
Combined with SM 113, IO 113 can monitor the
bearing temperature and rotor speed when the motor
is switched off.
24
English (GB)
Summary of Contents for ST-55-520
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